Surgical treatment using a medical needle such as ablator or biopsy has recently become popular due to relatively small incisions made in such a procedure. The surgical treatment is performed by inserting the medical needle into an internal region of a human body while referring to an internal image of the human body. Such surgical treatment, which is performed while observing internal organs of the human body with the help of a diagnostic imaging system, is referred to as an interventional treatment. The interventional treatment is performed by directing the medical needle to a lesion to be treated or examined through a skin with reference to images during the treatment. The images are acquired by employing a computerized tomography (CT) scanner, which is generally used in a radiology department, or a magnetic resonance imaging (MRI) system. Compared to a normal surgical treatment requiring relatively wide incisions to open the lesion, the interventional treatment has the advantages of low costs and obtaining effective operation results. This is because general anesthesia is not necessary for the interventional treatment and patients are subjected to less pain while benefiting from rapid recovery.
However, it is difficult to obtain such images in real time by using the CT scanner or the MRI system. Especially, when the interventional treatment is performed by using the CT scanner, both the patient and the operator are exposed to radiation for quite a long time. However, when the interventional treatment is performed by using an ultrasound diagnostic system, the images can be obtained in real time without affecting the human body. But, there is a problem since it is difficult to accurately recognize the lesion as well as the medical device (i.e., a needle) in the ultrasound image obtained by using the ultrasound system.